CN111320639B

CN111320639B - Organic compound, organic light emitting diode, and organic light emitting display device

Info

Publication number: CN111320639B
Application number: CN201911292260.XA
Authority: CN
Inventors: 尹大伟; 徐辅民; 金椿基; 崔东勋; 赵民柱; 崔树娜; 马莱斯哈姆·戈杜马拉
Original assignee: LG Display Co Ltd; Korea University Research and Business Foundation
Current assignee: LG Display Co Ltd; Korea University Research and Business Foundation
Priority date: 2018-12-14
Filing date: 2019-12-13
Publication date: 2022-12-09
Anticipated expiration: 2039-12-13
Also published as: CN111320639A; KR102633565B1; KR20200073598A; US20200190100A1; US11505557B2

Abstract

The present disclosure provides an organic compound of the following formula, and an organic light emitting diode and an OLED device including the same. The organic compound of the present disclosure may be included as a host in a light emitting material layer of an organic light emitting diode, thereby improving light emitting efficiency and lifetime of the organic light emitting diode and OLED device.

Description

Organic compound, organic light emitting diode, and organic light emitting display device

Cross Reference to Related Applications

This application claims the benefit of korean patent application No. 10-2018-0161942, filed in korea on 12, 14, 2018, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to an organic compound, and more particularly, to an organic compound having a high triplet energy level, and an organic light emitting diode and an Organic Light Emitting Display (OLED) device including the same.

Background

Recently, the demand for a flat panel display device having a small footprint is increasing. Among flat panel display devices, the technology of OLED devices, which include organic light emitting diodes and may be referred to as organic electroluminescent devices, is rapidly developing.

The organic light emitting diode emits light by: electrons from a cathode as an electron injection electrode and holes from an anode as a hole injection electrode are injected into the organic light-emitting layer, the electrons and the holes are combined, excitons are generated, and the excitons are shifted from an excited state to a ground state. A flexible transparent substrate such as a plastic substrate can be used as a base substrate on which elements are formed. In addition, the organic light emitting diode can operate at a voltage (e.g., 10V or less) lower than a voltage required to operate other display devices and has low power consumption. In addition, light from the organic light emitting diode has excellent color purity.

Recently, delayed fluorescence compounds are used for an emitter, i.e., a dopant, in an Emitting Material Layer (EML) of an organic light emitting diode. In the delayed fluorescent compound, triplet excitons are converted into singlet excitons by the reverse system cross-over (RISC) principle, so that the delayed fluorescent compound provides high luminous efficiency.

The delayed fluorescence compound may be referred to as a Field Activated Delayed Fluorescence (FADF) compound or a Thermally Activated Delayed Fluorescence (TADF) compound.

On the other hand, since the concentration quenching problem causes rapid decrease in the light emitting efficiency of the dopant, the EML further includes a host to prevent the above problem. In order to confine excitons in the delayed fluorescence compound, the host is required to have a higher triplet energy level than the dopant.

For example, for a delayed fluorescence compound emitting blue light, bis [2- (diphenylphosphino) -phenyl ] ether oxide (DPEPO) having a relatively high triplet energy level was introduced as a substrate. However, DPEPO has n-type properties because it contains a phosphine oxide moiety. Therefore, a recombination region of holes and electrons in the EML moves into the anode side.

On the other hand, when CBP having p-type characteristics is used as a host, a recombination region of holes and electrons in the EML moves into the cathode side.

That is, when the related art host material is used in the EML, the recombination region of holes and electrons is not located at the center of the EML, so that the light emitting efficiency and the lifetime of the organic light emitting diode and the OLED device are reduced.

Disclosure of Invention

The present invention is directed to organic compounds, organic light emitting diodes, and OLED devices that substantially obviate one or more of the problems associated with the limitations and disadvantages of the related conventional art.

Additional features and advantages of the invention are set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the disclosure. The objectives and other advantages of the invention will be realized and attained by the features particularly pointed out in the written description and drawings.

To achieve these and other advantages and in accordance with the purpose of embodiments of the invention, as embodied and broadly described herein, one aspect of the present invention is an organic compoundAn object:

wherein Ar1 is a heteroaryl group comprising a nitrogen atom (N), ar2 is a C6 to C30 aryl group, and wherein R is a C1 to C10 alkyl group.

Another aspect of the present invention is an organic light emitting diode including a first electrode; a second electrode facing the first electrode; and a first light-emitting material layer between the first electrode and the second electrode and containing an organic compound of:

Another aspect of the present invention is an organic light emitting display device, including: a substrate; an organic light emitting diode disposed on a substrate, the organic light emitting diode comprising: a first electrode, a second electrode facing the first electrode, and a light emitting material layer between the first electrode and the second electrode; and a thin film transistor positioned between the substrate and the organic light emitting diode and connected to the organic light emitting diode, wherein the light emitting material layer includes an organic compound of the formula:

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

Fig. 1 is a schematic circuit diagram of an OLED device of the present disclosure.

Fig. 2 is a schematic cross-sectional view of an OLED device of the present disclosure.

Fig. 3 is a schematic cross-sectional view of an organic light emitting diode according to a first embodiment of the present disclosure.

Fig. 4A and 4B are graphs showing a LUMO (lowest unoccupied molecular orbital) distribution and a HOMO (highest occupied molecular orbital) distribution, respectively, of compound 1 of the present disclosure.

Fig. 5A and 5B are graphs showing the LUMO distribution and HOMO distribution, respectively, of compound 2 of the present disclosure.

Fig. 6A and 6B are graphs showing the LUMO distribution and HOMO distribution, respectively, of compound 3 of the present disclosure.

Fig. 7A and 7B are graphs showing the LUMO distribution and HOMO distribution, respectively, of compound 4 of the present disclosure.

Fig. 8A and 8B are graphs showing the LUMO distribution and HOMO distribution, respectively, of compound 5 of the present disclosure.

Fig. 9A and 9B are graphs showing the LUMO distribution and HOMO distribution, respectively, of compound 6 of the present disclosure.

Fig. 10 is a graph showing hole transport characteristics of the organic compound of the present disclosure.

Fig. 11 is a graph illustrating the electron transfer characteristics of the organic compound of the present disclosure.

Fig. 12 is a schematic cross-sectional view of an organic light emitting diode according to a second embodiment of the present disclosure.

Fig. 13 is a schematic cross-sectional view of an organic light emitting diode according to a third embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to some examples and preferred embodiments, which are illustrated in the accompanying drawings.

As shown in fig. 1, the OLED device includes a gate line GL, a data line DL, a power line PL, a switching thin film transistor TFT Ts, a driving TFT Td, a storage capacitor Cst, and an organic light emitting diode D. The gate lines GL and the data lines DL cross each other to define the pixel regions P.

The switching TFT Ts is connected to the gate line GL and the data line DL, and the driving TFT Td and the storage capacitor Cst are connected to the switching TFT Ts and the power line PL. The organic light emitting diode D is connected to the driving TFT Td.

In the OLED device, when the switching TFT Ts is turned on by a gate signal applied through the gate line GL, a data signal from the data line DL is applied to the gate electrode of the driving TFT Td and the electrode of the storage capacitor Cst.

When the driving TFT Td is turned on by a data signal, a current is supplied from the power line PL to the organic light emitting diode D. Accordingly, the organic light emitting diode D emits light. In this case, when the driving TFT Td is turned on, the level of the current applied from the power line PL to the organic light emitting diode D is determined so that the organic light emitting diode D can generate a gray scale.

The storage capacitor Cst serves to maintain the voltage of the gate electrode of the driving TFT Td when the switching TFT Ts is turned off. Therefore, even if the switching TFT Ts is turned off, the level of the current applied from the power line PL to the organic light emitting diode D is maintained to the next frame.

Accordingly, the OLED device displays a desired image.

Fig. 2 is a schematic cross-sectional view of an OLED device of the present disclosure, and fig. 3 is a schematic cross-sectional view of an organic light emitting diode according to a first embodiment of the present disclosure.

As shown in fig. 2, the OLED device 100 includes a substrate 110, a driving TFT Td, and an organic light emitting diode D connected to the driving TFT Td.

The substrate 110 may be a glass substrate or a plastic substrate. For example, the substrate 110 may be a polyimide substrate.

A buffer layer 120 is formed on the substrate, and a driving TFT Td is formed on the buffer layer 120. The buffer layer 120 may be omitted.

A semiconductor layer 122 is formed on the buffer layer 120. The semiconductor layer 122 may include an oxide semiconductor material or polysilicon.

When the semiconductor layer 122 includes an oxide semiconductor material, a light-shielding pattern (not shown) may be formed under the semiconductor layer 122. Light reaching the semiconductor layer 122 is shielded or blocked by the light blocking pattern so that thermal degradation of the semiconductor layer 122 can be prevented. On the other hand, when the semiconductor layer 122 includes polycrystalline silicon, impurities may be doped into both sides of the semiconductor layer 122.

A gate insulating layer 124 is formed on the semiconductor layer 122. The gate insulating layer 124 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 130 formed of a conductive material such as metal is formed on the gate insulating layer 124 corresponding to the center of the semiconductor layer 122.

In fig. 2, a gate insulating layer 124 is formed on the entire surface of the substrate 110. Alternatively, the gate insulating layer 124 may be patterned to have the same shape as the gate electrode 130.

An interlayer insulating layer 132 formed of an insulating material is formed on the gate electrode 130. The interlayer insulating layer 132 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating layer 132 includes a first contact hole 134 and a second contact hole 136 exposing both sides of the semiconductor layer 122. The first contact hole 134 and the second contact hole 136 are located at both sides of the gate electrode 130 to be spaced apart from the gate electrode 130.

The first contact hole 134 and the second contact hole 136 are formed through the gate insulating layer 124. Alternatively, when the gate insulating layer 124 is patterned to have the same shape as the gate electrode 130, the first and second contact holes 134 and 136 are formed only through the interlayer insulating layer 132.

A source electrode 140 and a drain electrode 142 formed of a conductive material such as metal are formed on the interlayer insulating layer 132.

The source and drain

electrodes

140 and 142 are spaced apart from each other with respect to the gate electrode 130 and contact both sides of the semiconductor layer 122 through the first and second contact holes 134 and 136, respectively.

The semiconductor layer 122, the gate electrode 130, the source electrode 140, and the drain electrode 142 constitute a driving TFT Td. The driving TFT Td serves as a driving element.

In the driving TFT Td, the gate electrode 130, the source electrode 140, and the drain electrode 142 are located above the semiconductor layer 122. That is, the driving TFT Td has a coplanar structure.

Alternatively, in the driving TFT Td, the gate electrode may be positioned below the semiconductor layer, and the source and drain electrodes may be positioned above the semiconductor layer, so that the driving TFT Td may have an inverted staggered structure. In this case, the semiconductor layer may include amorphous silicon.

Although not shown, the gate lines and the data lines cross each other to define pixel regions, and switching TFTs are formed to be connected to the gate lines and the data lines. The switching TFT is connected to a driving TFT Td as a driving element.

In addition, power lines, which may be formed parallel to and spaced apart from one of the gate lines and the data lines, and a storage capacitor for holding a voltage of the gate electrode of the driving TFT Td for one frame may be further formed.

A passivation layer 150 including a drain contact hole 152 exposing the drain electrode 142 of the driving TFT Td is formed to cover the driving TFT Td.

A first electrode 160 is separately formed in each pixel region, and the first electrode 160 is connected to the drain electrode 142 of the driving TFT Td through the drain contact hole 152. The first electrode 160 may be an anode, and may be formed of a conductive material having a relatively high work function. For example, the first electrode 160 may be formed of a transparent conductive material such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO).

When the OLED device 100 operates in a top emission type, a reflective electrode or a reflective layer may be formed under the first electrode 160. For example, the reflective electrode or the reflective layer may be formed of an aluminum-palladium-copper (APC) alloy.

A bank layer 166 is formed on the passivation layer 150 to cover an edge of the first electrode 160. That is, the bank layer 166 is located at the boundary of the pixel region and exposes the center of the first electrode 160 in the pixel region.

An organic light emitting layer 162 is formed on the first electrode 160. The organic light emitting layer 162 may have a single-layer structure of a light emitting material layer including a light emitting material. In order to improve the light emitting efficiency of the OLED device, the organic light emitting layer 162 may have a multi-layer structure.

For example, referring to fig. 3, the organic emission layer 162 may include an Emission Material Layer (EML) 240 between the first electrode 160 and the second electrode 164, a Hole Transport Layer (HTL) 220 between the first electrode 160 and the EML 240, and an Electron Transport Layer (ETL) 260 between the second electrode 164 and the EML 240.

In addition, the organic light emitting layer 162 may further include a Hole Injection Layer (HIL) 210 between the first electrode 160 and the HTL 220 and an Electron Injection Layer (EIL) 270 between the second electrode 164 and the ETL 260.

Also, the organic light emitting layer 162 may further include an Electron Blocking Layer (EBL) 230 between the HTL 220 and the EML 240 and a Hole Blocking Layer (HBL) 250 between the EML 240 and the ETL 260.

A second electrode 164 is formed over the substrate 110 on which the organic light emitting layer 162 is formed. The second electrode 164 covers the entire surface of the display region, and may be formed of a conductive material having a relatively low work function to serve as a cathode. For example, the second electrode 164 may be formed of aluminum (Al), magnesium (Mg), or Al — Mg alloy.

The first electrode 160, the organic light emitting layer 162, and the second electrode 164 constitute an organic light emitting diode D.

An encapsulation film 170 is formed on the second electrode 164 to prevent moisture from penetrating into the organic light emitting diode D. The encapsulation film 170 includes a first inorganic insulating layer 172, an organic insulating layer 174, and a second inorganic insulating layer 176, which are sequentially stacked, but is not limited thereto.

A polarizing plate (not shown) for reducing reflection of ambient light may be disposed on the top emission type organic light emitting diode D. For example, the polarizing plate may be a circular polarizing plate.

In addition, a cover window (not shown) may be attached to the encapsulation film 170 or the polarizing plate. In this case, the substrate 110 and the cover window have flexible characteristics, so that a flexible OLED device may be provided.

The organic light emitting layer 162 includes an organic compound of formula 1.

[ formula 1]

In formula 1, ar1 is a heteroaryl group including a nitrogen atom (N), and Ar2 is a C6 to C30 aryl group. R is C1 to C10 alkyl.

For example, ar1 may be represented by one of formulas 2-1 to 2-5.

[ formula 2-1]

[ formula 2-2]

[ formulas 2 to 3]

[ formulas 2 to 4]

[ formulas 2 to 5]

In formulas 2-1 and 2-2, R1 and R2 may each be independently selected from hydrogen, carbazolyl, and arylamine. In formulae 2-3 and 2-4, R3 and R4 may each independently be selected from C1 to C10 alkyl groups and C6 to C30 aryl groups, or R3 and R4 may be combined (or bonded) to form a fused ring. R5 and R6 may each be independently selected from hydrogen, carbazolyl, and arylamine. In formulas 2-5, R7 and R8 may each be independently selected from hydrogen, carbazolyl, and arylamine groups.

For example, ar1 in formula 1 may be selected from formula 3.

[ formula 3]

In formula 1, ar2 may be phenyl and R may be methyl.

Since the organic compounds of the present disclosure comprise a benzopyran-pyrazole parent nucleus, the organic compounds have a high triplet energy level. (high triplet energy level)

In addition, in the organic compound of the present disclosure, since the benzopyran-pyrazole parent nucleus serves as an electron acceptor, and an electron donor moiety (e.g., carbazole) is linked (or bonded) to the electron acceptor moiety, the organic compound of the present disclosure has a bipolar property (characteristic).

Therefore, organic light emitting diodes and OLED devices including an organic compound as a host in EMLs have advantages in light emitting efficiency and lifetime.

For example, since DPEPO compounds, which have relatively high triplet energy levels and can be used as a matrix, have n-type characteristics, a recombination region of holes and electrons is not located at the center of the EML. However, since the organic compound of the present disclosure results in a good balance of holes and electrons due to high triplet energy levels and bipolar characteristics, a recombination region of holes and electrons is located at the center of the EML. Accordingly, the organic light emitting diode and the OLED device have improved light emitting efficiency without life reduction.

The organic compound of the present disclosure is contained in the organic light emitting layer 162, preferably in the EML 240. The organic compound serves as a host, and the EML 240 may further include a dopant. For example, the weight percentage of dopant relative to the matrix may be about 1% to 40%. The dopant may be at least one of a delayed fluorescence dopant, a phosphorescent dopant, and a fluorescent dopant.

When EML 240 contains a delayed fluorescence dopant (delayed fluorescence compound) and an organic compound of the present disclosure as a host, HOMO "HOMO of the host _Substrate And delayed fluorescence dopingHOMO "of agents _{Dopant agent} "difference or matrix LUMO", LUMO _Substrate "LUMO with delayed fluorescence dopant" LUMO _{Dopant agent} The difference is less than about 0.5eV. In this case, the charge transfer efficiency from the host to the dopant can be improved.

The triplet level of the delayed fluorescence dopant is less than the triplet level of the host, and the difference between the singlet level of the delayed fluorescence dopant and the triplet level of the delayed fluorescence dopant is less than 0.3eV. (Δ E) _ST Less than or equal to 0.3eV. ) Current difference "Δ E _ST When the ratio is smaller, the luminous efficiency is higher. Further, even if the difference between the singlet energy level of the delayed fluorescence dopant and the triplet energy level of the delayed fluorescence dopant is "Δ E _ST "about 0.3eV (relatively large), singlet excitons and triplet excitons may also be converted to intermediate states.

The EML 240 may include the organic compound of the present disclosure as a host, a delayed fluorescence dopant as a first dopant, and a fluorescence dopant as a second dopant. The weight percentage of the sum of the first dopant and the second dopant relative to the matrix may be about 1 wt% to 40 wt%.

The first dopant may have a singlet energy level less than that of the host and greater than that of the second dopant. The first dopant may have a triplet energy level less than that of the host and greater than that of the second dopant.

Since the EML 240 includes a host and a first dopant and a second dopant, the light emitting efficiency may be improved by the first dopant, and the color purity may be improved by the second dopant. That is, after energy is transferred from the host into the first dopant, the singlet energy and the triplet energy of the first dopant are transferred into the second dopant, and light emission is provided from the second dopant. Accordingly, the quantum efficiency (light emitting efficiency) of the organic light emitting diode D increases, and the full width at half maximum (FWHM) of the organic light emitting diode D becomes narrow.

The delayed fluorescence dopant as the first dopant has high quantum efficiency. However, since light emitted from the delayed fluorescence dopant has a wide FWHM, the light from the delayed fluorescence dopant has poor color purity. On the other hand, the fluorescent dopant as the second dopant has a narrow FWHM and a high color purity. However, since the triplet energy of the fluorescent dopant does not participate in light emission, the fluorescent dopant has low quantum efficiency.

However, since the EML 240 includes the first dopant (i.e., delayed fluorescence compound) and the second dopant (i.e., fluorescent dopant), the organic light emitting diode D has advantages in both light emitting efficiency and color purity.

In addition, since the organic compound of the present disclosure having a high triplet energy level and a bipolar characteristic is used as a host, the light emitting efficiency of the organic light emitting diode D is further improved.

For example, the organic compound of the present disclosure in formula 1 may be one of the compounds in formula 4.

[ formula 4]

[ Synthesis of organic Compound ]

1. Synthesis of Compound 1

(1) Compound B

[ reaction formula 1-1]

In a reaction vessel, compound A (1.0 g,3.8 mmol) was dissolved in methanol (5 ml) and stirred at a temperature of 60 ℃. After a mixed solution of phenylhydrazine (0.41ml, 4.1mmol), acetic acid (10 ml) and distilled water (5 ml) was slowly added to the reaction vessel using a dropping funnel, the mixture was stirred for 30 minutes. The mixture was cooled to room temperature, and an orange-red precipitate was separated by distillation under reduced pressure. The precipitate was washed with distilled water to obtain compound B (1.26 g, yield = 94%).

(2) Compound C

[ reaction formulae 1-2]

Copper (II) acetate monohydrate (0.34g, 1.7 mmol) and compound B (1.2g, 3.4 mmol) were dissolved in 1,4-dioxane (100 ml) and stirred at a temperature of 70 ℃ for 5 hours. The mixture was cooled to room temperature, and the precipitate was removed by distillation under the reduced pressure. Compound C (1.1 g, yield = 92%) was obtained by silica gel column chromatography using a mixed solution of ethyl acetate and hexane (volume ratio = 1:9).

(3) Compound 1

[ reaction formulas 1 to 3]

Under nitrogen, compound C (1.0g, 2.8mmol), compound D (0.52g, 3.1mmol) and K were mixed ₃ PO ₄ (1.8g, 8.4 mmol) was dissolved in toluene (30 ml) and refluxed for 15 minutes. The mixture was heated at a temperature of 60 ℃. Pd (OAc) ₂ (0.019g, 0.08mmol) and tri-tert-butylphosphine (0.68mL, 0.17mmol, 50 wt% in xylene) were added to the mixture and refluxed for 8 hours. After the mixture was cooled to room temperature and filtered through a reduced pressure filter, CH was used ₂ Cl ₂ The mixture is washed. After obtaining the resultant by removing the organic layer, use of CH is performed ₂ Cl ₂ And hexane (volume ratio = 1:1), thereby obtaining compound 1 (1.15 g, yield = 93%) as a white color.

2. Synthesis of Compound 2

[ reaction formula 2]

Compound E was used instead of compound D in the synthesis of compound 1 to obtain compound 2 (2.2 g, yield = 86%).

3. Synthesis of Compound 3

[ reaction formula 3]

In a reaction vessel under nitrogen, compound C (1.30g, 3.66mmol), compound F (0.95g, 4.54mmol) and sodium tert-butoxide (1.00g, 10.4 mmol) were dissolved in toluene (200 ml). Will contain Pd (dba) ₂ (0.3g, 5.22mmol) and P (tBu) ₃ A solution (30 ml) of (0.22g, 1.09mmol) in toluene was slowly added to the reaction vessel and refluxed for 15 hours. After the mixture was cooled to room temperature, the precipitate was removed using celite, and the solvent was dried. Compound 3 (1.52 g, yield = 86%) was obtained by silica gel column chromatography.

4. Synthesis of Compound 4

[ reaction formula 4]

Compound G was used instead of compound F in the synthesis of compound 3 to obtain compound 4 (1.68G, yield = 74%).

5. Synthesis of Compound 5

[ reaction formula 5]

Compound H was used instead of compound F in the synthesis of compound 3 to obtain compound 5 (1.26 g, yield = 75%).

6. Synthesis of Compound 6

[ reaction formula 6]

Compound I was used instead of compound F in the synthesis of compound 3 to obtain compound 6 (1.09 g, yield = 49%).

Physical properties of the compounds 1 to 6 in formula 4, i.e., HOMO level, LUMO level, energy bandgap (Eg), singlet level (S1) and triplet level (T1), were measured and listed in Table 1 (unit: [ eV ]). The LUMO distribution and HOMO distribution of compound 1 are shown in fig. 4A and 4B, respectively, and the LUMO distribution and HOMO distribution of compound 2 are shown in fig. 5A and 5B, respectively. The LUMO distribution and HOMO distribution of compound 3 are shown in fig. 6A and 4B, respectively, and the LUMO distribution and HOMO distribution of compound 4 are shown in fig. 7A and 7B, respectively. The LUMO distribution and HOMO distribution of compound 5 are shown in fig. 8A and 8B, respectively, and the LUMO distribution and HOMO distribution of compound 6 are shown in fig. 9A and 9B, respectively.

TABLE 1

	HOMO	LUMO	Eg	S1	T1
						Compound 1	-1.70	-5.51	3.81	3.26	3.00
Compound 2	-1.80	-5.25	3.45	3.08	2.97
						Compound 3	-1.69	-5.16	3.37	2.88	2.85
Compound 4	-1.76	-5.20	3.44	2.86	2.82
						Compound 5	-1.75	-5.21	3.06	2.50	2.86
Compound 6	-1.67	-5.25	3.58	3.00	2.97

As shown in table 1, the organic compounds of the present disclosure have higher triplet energy levels. Thus, the organic compounds used as matrices in EML provide high energy efficiency.

[ hole-only device ]

At about 10 ^-7 In the vacuum chamber, layers are sequentially deposited on the ITO substrate.

(1) a first HTL (20 nm, formula 5), (2) a matrix layer (50 nm), (3) a second HTL (20 nm, formula 5), and (4) a cathode (100nm, al).

1. Example 1

Compound 3 of formula 4 was used to form a matrix layer.

2. Example 2

The matrix layer is formed using compound 4 of formula 4.

3. Comparative example 1

The DPEPO compound is used to form the matrix layer.

[ formula 5]

The current densities of the hole-only devices in examples 1 and 2 and comparative example 1 were measured and are shown in fig. 10.

As shown in fig. 10, the hole mobility of the hole-only device using the organic compound of the present disclosure is improved compared to the hole-only device using the DPEPO compound as a matrix.

[ electronic devices only ]

(1) a first ETL (20 nm, formula 6), (2) a matrix layer (50 nm), (3) a second ETL (20 nm, formula 6), (4) EIL (1.5 nm, lif), and (5) a cathode (100nm, al).

1. Example 3

The matrix layer is formed using compound 3 of formula 4.

2. Example 4

The matrix layer is formed using compound 4 of formula 4.

3. Comparative example 2

The DPEPO compound is used to form the matrix layer.

[ formula 6]

The current densities of the electronic-only devices in examples 3 and 4 and comparative example 2 were measured and are shown in fig. 11.

As shown in fig. 11, the electron mobility of the electron-only device using the organic compound of the present disclosure is improved compared to the electron-only device using the DPEPO compound as a matrix.

[ organic light emitting diode ]

At about 10 ^-7 In the vacuum chamber, layers are sequentially deposited on the ITO substrate. A dopant that delays the fluorescence of the compound is used.

(a)HIL(

Formula 7), (b) HTL: (b)

Formula 5), (c) EBL: (

Formula 8), (d) EML (

Host: dopant (10% by weight, formula 9)), (e) HBL (g: (e)), (e)

Formula 10), (f) ETL (f)

Formula 6), (g) EIL: (g)

LiF) and (h) a cathode (b)

Al)。

[ formula 7]

(1) Example 5 (Ex 5)

Compound 1 of formula 4 was used as a substrate.

(2) Example 6 (Ex 6)

Compound 2 of formula 4 was used as a substrate.

(3) Example 7 (Ex 7)

Compound 3 of formula 4 was used as a substrate.

(4) Example 8 (Ex 8)

Compound 4 of formula 4 was used as a substrate.

(5) Example 9 (Ex 9)

Compound 5 of formula 4 was used as a substrate.

(6) Example 10 (Ex 10)

Compound 6 of formula 4 was used as a substrate.

[ formula 7]

[ formula 8]

[ formula 9]

[ formula 10]

The characteristics of Ex5 to Ex10 organic light emitting diodes were measured. The driving voltage (Von), the light emission peak (λ) of the organic light emitting diode were measured using a current source "KEITHLEY" and a photometer "PR 650 _max ) Current Efficiency (CE), power Efficiency (PE), external Quantum Efficiency (EQE) and CIE color coordinates are listed in table 2.

TABLE 2

^a Luminance of 1cd m ^-2 The lighting voltage of the time. ^b 1000 cd m ^-2 The maximum EL wavelength of (b). ^d Maximum current efficiency. ^e Maximum power efficiency. ^f External quantum efficiency at maximum, 100cd m ^-2 And 500cd m ^-2 。 ^g InternationalCommittee for illumination (Commission Internationale de l'Elcairage)，1000cd ^-2 m is lower.

As shown in table 2, the organic light emitting diodes of Ex5 to Ex10 using the organic compound of the present disclosure as a host provide high luminous efficiency.

As shown in fig. 12, the organic light emitting diode D includes a first electrode 160 and a second electrode 164 facing each other with an organic light emitting layer 162 therebetween. The organic emission layer 162 includes an EML 340 including a first layer 342 and a second layer 344 and positioned between the first electrode 160 and the second electrode 164, an HTL 320 between the first electrode 160 and the EML 340, and an ETL 360 between the second electrode 164 and the EML 340.

In addition, the organic light emitting layer 162 may further include an HIL 310 between the first electrode 160 and the HTL 320 and an EIL 370 between the second electrode 164 and the ETL 360.

Also, the organic light emitting layer 162 may further include an EBL 330 between the HTL 320 and the EML 340 and an HBL 350 between the EML 340 and the ETL 360.

For example, in the EML 340, the first layer 342 (e.g., a first luminescent material layer) may include an organic compound of the present disclosure as a first host and a delayed fluorescence dopant as a first dopant, and the second layer 344 (e.g., a second luminescent material layer) may include a second host and a fluorescence dopant as a second dopant. Alternatively, the second layer 344 may include an organic compound of the present disclosure as a first host and a delayed fluorescence dopant as a first dopant, and the first layer 342 may include a second host and a fluorescence dopant as a second dopant. The second matrix may be an organic compound of the present disclosure. The singlet energy level of the delayed fluorescent dopant is greater than the singlet energy level of the fluorescent dopant.

An organic light emitting diode will be described in which the first layer 342 contains a delayed fluorescence dopant and the second layer 344 contains a fluorescence dopant.

In the organic light emitting diode D, the singlet state level and the triplet state level of the delayed fluorescent dopant are transferred into the fluorescent dopant, so that light emission is generated from the fluorescent dopant. Accordingly, the quantum efficiency of the organic light emitting diode D increases, and the FWHM of the organic light emitting diode D is narrowed.

The delayed fluorescence dopant as the first dopant has high quantum efficiency. However, since light emitted from the delayed fluorescence dopant has a wide FWHM, the light from the delayed fluorescence dopant has poor color purity. On the other hand, the fluorescent dopant as the second dopant has a narrow FWHM and a high color purity. However, since the triplet level of the fluorescent dopant does not participate in light emission, the fluorescent dopant has low quantum efficiency.

Since the EML 340 of the organic light emitting diode D in the present disclosure includes the first layer 342 and the second layer 344, the first layer 342 contains the delayed fluorescence dopant and the second layer 344 contains the fluorescence dopant, the organic light emitting diode D has advantages in both light emitting efficiency and color purity.

The triplet state level of the delayed fluorescence dopant is converted into the singlet state level of the delayed fluorescence dopant by the RISC effect, and the singlet state level of the delayed fluorescence dopant is transferred to the singlet state level of the fluorescence dopant. That is, the difference between the triplet level of the delayed fluorescence dopant and the singlet level of the delayed fluorescence dopant is less than 0.3eV, so that the triplet level of the delayed fluorescence dopant is converted into the singlet level of the delayed fluorescence dopant by the RISC effect.

Therefore, the delayed fluorescence dopant has an energy transfer function, and the first layer 342 including the delayed fluorescence dopant does not participate in light emission. Light emission is generated in the second layer 344 including the fluorescent dopant.

The triplet level of the delayed fluorescence dopant is converted into the singlet level of the delayed fluorescence dopant by the RISC effect. In addition, since the singlet energy level of the delayed fluorescent dopant is higher than the singlet energy level of the fluorescent dopant, the singlet energy level of the delayed fluorescent dopant is transferred into the singlet energy level of the fluorescent dopant. Accordingly, the fluorescent dopant emits light using the singlet level and the triplet level, thereby improving the quantum efficiency (light emitting efficiency) of the organic light emitting diode D.

In other words, the organic light emitting diode D (of fig. 2) and the OLED device 100 including the organic light emitting diode D have advantages in both light emitting efficiency and color purity.

In each of the first and

second layers

342 and 344, the first and second hosts may have a weight percentage greater than the delayed fluorescence dopant and the fluorescence dopant, respectively. Further, the weight percentage of the delayed fluorescence dopant in the first layer 342 may be greater than the weight percentage of the fluorescence dopant in the second layer 344. Therefore, energy transfer from the delayed fluorescent dopant to the fluorescent dopant is sufficiently generated.

The singlet energy level of the first host is greater than the singlet energy level of the delayed fluorescence dopant, and the triplet energy level of the first host is greater than the triplet energy level of the delayed fluorescence dopant. Further, the singlet energy level of the second host is greater than the singlet energy level of the fluorescent dopant.

When this condition is not satisfied, quenching or energy transfer from the host to the dopant occurs at the first dopant and the second dopant, and thus the quantum efficiency of the organic light emitting diode D is decreased.

As described above, since the organic compound of the present disclosure has a high triplet energy level, the energy transfer efficiency into the delayed fluorescence compound is increased, thereby improving the light emitting efficiency of the organic light emitting diode D. In addition, the back transition of excitons generated from the delayed fluorescence dopant to the host is substantially prevented.

In addition, since the organic compound of the present disclosure having a bipolar property is included in the first layer 342 and/or the second layer 344 as a host, a recombination region of holes and electrons is located at the center of the first layer 342 and/or the second layer 344. Accordingly, the light emitting efficiency and the lifetime of the organic light emitting diode D are improved.

For example, the second host included in the second layer 344 together with the fluorescent dopant may be the same as the material of the HBL 350. In this case, the second layer 344 may have a hole blocking function and a light emitting function. That is, the second layer 344 may function as a buffer layer for blocking holes. When the HBL 350 is omitted, the second layer 344 functions as a light emitting layer and a hole blocking layer.

When the first layer 342 includes a fluorescent dopant and the second layer 344 includes a delayed fluorescent dopant, the first host of the first layer 342 can be the same material as the EBL 330. In this case, the first layer 342 may have an electron blocking function and a light emitting function. That is, the first layer 342 may function as a buffer layer for blocking electrons. When the EBL 330 is omitted, the first layer 342 functions as a light emitting layer and an electron blocking layer.

Fig. 13 is a schematic cross-sectional view of an organic light emitting diode of the present disclosure.

As shown in fig. 13, the organic light emitting diode D includes a first electrode 160 and a second electrode 164 facing each other with an organic light emitting layer 162 therebetween. The organic emission layer 162 includes an EML 440 including a first layer 442, a second layer 444, and a third layer 446 and positioned between the first electrode 160 and the second electrode 164, an HTL 420 between the first electrode 160 and the EML 440, and an ETL 460 between the second electrode 164 and the EML 440.

In addition, the organic light emitting layer 162 may further include an HIL 410 between the first electrode 160 and the HTL 420 and an EIL 470 between the second electrode 164 and the ETL 460.

Also, the organic light emitting layer 162 may further include an EBL 430 between the HTL 420 and the EML 440 and an HBL 450 between the EML 440 and the ETL 460.

In the EML 440, the first layer 442 is located between the second layer 444 and the third layer 446. That is, the second layer 444 is located between the EBL 430 and the first layer 442, and the third layer 446 is located between the first layer 442 and the HBL 450.

The first layer 442 (e.g., a first luminescent material layer) may include an organic compound of the present disclosure as a first host and a delayed fluorescence dopant as a first dopant, and the second layer 444 (e.g., a second luminescent material layer) may include a second host and a fluorescence dopant as a second dopant. The third layer 446 (e.g., a third luminescent material layer) may include a third host and include a fluorescent dopant as a third dopant. The fluorescent dopants in the second and

third layers

444, 446 can be the same or different. The second and third substrates may be organic compounds of the present disclosure. The singlet energy level of the delayed fluorescent dopant is greater than the singlet energy level of the fluorescent dopant.

In the organic light emitting diode D, the singlet state level and the triplet state level of the delayed fluorescent dopant are transferred into the fluorescent dopant in the second layer 444 and/or the third layer 446, so that light emission is generated by the fluorescent dopant. Accordingly, the quantum efficiency of the organic light emitting diode D increases, and the FWHM of the organic light emitting diode D is narrowed.

In each of the first, second, and

third layers

442, 444, and 446, the first through third hosts may have a weight percentage greater than the first through third dopants, respectively. Further, the weight percentage of the delayed fluorescence dopant (i.e., the first dopant) in the first layer 442 may be greater than the respective weight percentages of the fluorescence dopant (i.e., the second dopant) in the second layer 444 and the fluorescence dopant (i.e., the third dopant) in the third layer 446.

The singlet energy level of the first host is greater than the singlet energy level of the delayed fluorescence dopant, and the triplet energy level of the first host is greater than the triplet energy level of the delayed fluorescence dopant. Further, the singlet energy level of the second host in the second layer 444 is greater than the singlet energy level of the fluorescent dopant, and the singlet energy level of the third host in the third layer 446 is greater than the singlet energy level of the fluorescent dopant.

As described above, since the organic compound of the present disclosure has a high triplet energy level, the energy transfer efficiency to the delayed fluorescence compound is increased, thereby improving the light emitting efficiency of the organic light emitting diode D. In addition, the back transition of excitons generated from the delayed fluorescence dopant to the host is substantially prevented.

Also, since the organic compound of the present disclosure having a bipolar property is included in each of the first layer 442, and/or the second layer 444 and the third layer 446 as a host, a recombination region of holes and electrons is located at the center of each of the first layer 442, and/or the second layer 444 and the third layer 446. Accordingly, the light emitting efficiency and the lifetime of the organic light emitting diode D are improved.

For example, the second matrix in the second layer 444 may be the same material as the EBL 430. In this case, the second layer 444 may have an electron blocking function and a light emitting function. That is, the second layer 444 may function as a buffer layer for blocking electrons. When the EBL 430 is omitted, the second layer 444 functions as a light emitting layer and an electron blocking layer.

The third matrix in the third layer 446 may be the same material as the HBL 450. In this case, the third layer 446 may have a hole blocking function and a light emitting function. That is, the third layer 446 may function as a buffer layer for blocking holes. When the HBL 450 is omitted, the third layer 446 functions as a light-emitting layer and a hole-blocking layer.

The second matrix in the second layer 444 may be the same material as the EBL 430 and the third matrix in the third layer 446 may be the same material as the HBL 450. In this case, the second layer 444 may have an electron blocking function and a light emitting function, and the third layer 446 may have a hole blocking function and a light emitting function. That is, the second layer 444 may function as a buffer layer for blocking electrons, and the third layer 446 may function as a buffer layer for blocking holes. When the EBL 430 and the HBL 450 are omitted, the second layer 444 functions as a light emitting layer and an electron blocking layer, and the third layer 446 functions as a light emitting layer and a hole blocking layer.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. An organic compound of formula 1:

[ formula 1]

Wherein Ar2 is a phenyl group, or a substituted phenyl group,

wherein R is methyl, and

wherein Ar1 is selected from formula 2:

[ formula 2]

2. The organic compound of claim 1, wherein the organic compound is selected from the group consisting of:

3. an organic light emitting diode comprising:

a first electrode;

a second electrode facing the first electrode; and

a first luminescent material layer between the first electrode and the second electrode and including an organic compound of formula 1 as a first host and a delayed fluorescence compound as a first dopant:

[ formula 1]

Wherein Ar2 is a phenyl group, or a substituted phenyl group,

wherein R is methyl, and

wherein Ar1 is selected from formula 2:

[ formula 2]

4. The organic light-emitting diode according to claim 3, wherein a triplet energy level of the first host is larger than a triplet energy level of the first dopant.

5. The organic light-emitting diode of claim 3, wherein a difference between a HOMO level of the first host and a HOMO level of the first dopant, or a difference between a LUMO level of the first host and a LUMO level of the first dopant, is less than 0.5eV.

6. An organic light-emitting diode according to claim 3, wherein the first luminescent material layer further comprises a fluorescent compound as a second dopant, the singlet energy level of the first dopant being greater than the singlet energy level of the second dopant.

7. The organic light-emitting diode according to claim 6, wherein the triplet energy level of the first dopant is smaller than the triplet energy level of the first host and larger than the triplet energy level of the second dopant.

8. The organic light emitting diode of claim 3, further comprising:

a second light emitting material layer including a second host and a fluorescent compound as a second dopant and located between the first electrode and the first light emitting material layer.

9. The organic light emitting diode of claim 8, further comprising:

an electron blocking layer between the first electrode and the second light emitting material layer,

wherein the second matrix is the same material as the electron blocking layer.

10. The organic light emitting diode of claim 8, further comprising:

a third light emitting material layer including a third host and a fluorescent compound as a third dopant and located between the second electrode and the first light emitting material layer.

11. The organic light emitting diode of claim 10, further comprising:

a hole blocking layer between the second electrode and the third light emitting material layer,

wherein the third host is the same material as the hole blocking layer.

12. The organic light-emitting diode of claim 10, wherein the first dopant has a singlet energy level that is greater than each of the second dopant's singlet energy level and the third dopant's singlet energy level.

13. The organic light-emitting diode of claim 10, wherein the singlet and triplet energy levels of the first host are greater than the singlet and triplet energy levels of the first dopant, respectively, and

wherein the singlet energy level of the second host is greater than the singlet energy level of the second dopant and the singlet energy level of the third host is greater than the singlet energy level of the third dopant.

14. The organic light-emitting diode of claim 8, wherein the singlet energy level of the first dopant is greater than the singlet energy level of the second dopant.

15. An organic light emitting diode according to claim 3, wherein the organic compound is selected from:

16. an organic light emitting display device comprising:

a substrate;

an organic light emitting diode disposed on the substrate, the organic light emitting diode comprising:

a first electrode;

a second electrode facing the first electrode; and

a light emitting material layer between the first electrode and the second electrode; and

a thin film transistor positioned between the substrate and the organic light emitting diode and connected to the organic light emitting diode,

wherein the light emitting material layer comprises an organic compound of formula 1 as a host and a delayed fluorescence compound as a dopant:

[ formula 1]

Wherein Ar2 is a phenyl group, or a substituted phenyl group,

wherein R is methyl, and

wherein Ar1 is selected from formula 2:

[ formula 2]

17. An organic light-emitting display device according to claim 16, wherein the organic compound is selected from: